A hydraulic brake system mounted on a vehicle includes a system configured to generate a braking force depending on working fluid supplied by a liquid-pressure source device that can regulate a hydraulic pressure of the working fluid without depending on an operational force applied to a brake member by a driver. In such a system, an electric power supplied to the liquid-pressure source device is controlled to change a supply pressure that is the hydraulic pressure of the working fluid supplied by the liquid-pressure source device, which allows generation of an appropriate braking force based on the braking operation of the driver. The hydraulic brake system includes another type of system equipped with the ABS valve device in order to restrain locks, skids, and the like of wheels. Patent Documents described below disclose one example of the brake system including the liquid-pressure source device and the ABS valve device.